<template>
  <canvas class="bgCanvas"
          width="100%"
          height="100%"></canvas>
</template>

<script>
export default {
  // es6的暴露
  // 挂载之后的钩子函数  画canvase
  beforeMount () { },
  methods: {
    setWidth (canvas) {
      //设置canvas的宽和高
      console.log(555555555);
      canvas.width = window.innerWidth;
      canvas.height = window.innerHeight;
    }
  },
  mounted: function () {
    //挂载后执行的方法
    //    获取canvas
    var canvas = document.getElementsByClassName("bgCanvas")[0],
      ctx = canvas.getContext("2d"); //2d的画板
    //    设置宽高

    this.setWidth(canvas);
    window.addEventListener(
      "resize",
      () => {
        this.setWidth(canvas);
      },
      true
    );
    ctx.lineWidth = 0.3;

    ctx.strokeStyle = new Color(150).style;
    var dotsNomber = 400; // 点点数
    if (canvas.width < 1400) {
      dotsNomber = 200;
    }

    var mousePosition = {
      x: (30 * canvas.width) / 100,
      y: (30 * canvas.height) / 100
    };

    var dots = {
      nb: dotsNomber,
      distance: 100,
      d_radius: 150,
      array: []
    };

    function colorValue (min) {
      //255-0
      return Math.floor(Math.random() * 255 + min);
    }

    function createColorStyle (r, g, b) {
      // 颜色的rgba的表示方法
      return "rgba(" + r + "," + g + "," + b + ", 0.8)";
    }

    function mixComponents (comp1, weight1, comp2, weight2) {
      return (comp1 * weight1 + comp2 * weight2) / (weight1 + weight2);
    }

    function averageColorStyles (dot1, dot2) {
      var color1 = dot1.color,
        color2 = dot2.color;

      var r = mixComponents(color1.r, dot1.radius, color2.r, dot2.radius),
        g = mixComponents(color1.g, dot1.radius, color2.g, dot2.radius),
        b = mixComponents(color1.b, dot1.radius, color2.b, dot2.radius);
      return createColorStyle(Math.floor(r), Math.floor(g), Math.floor(b));
    }

    function Color (min) {
      min = min || 0;
      this.r = colorValue(min);
      this.g = colorValue(min);
      this.b = colorValue(min);
      this.style = createColorStyle(this.r, this.g, this.b);
    }

    function Dot () {
      this.x = Math.random() * canvas.width;
      this.y = Math.random() * canvas.height;

      this.vx = -0.5 + Math.random();
      this.vy = -0.5 + Math.random();

      this.radius = Math.random() * 2;

      this.color = new Color();
      //console.log(this);
    }

    Dot.prototype = {
      draw: function () {
        ctx.beginPath();
        ctx.fillStyle = this.color.style;
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
        ctx.fill();
      }
    };

    function createDots () {
      for (var i = 0; i < dots.nb; i++) {
        dots.array.push(new Dot());
      }
    }

    function moveDots () {
      for (var i = 0; i < dots.nb; i++) {
        var dot = dots.array[i];

        if (dot.y < 0 || dot.y > canvas.height) {
          // dot.vx = dot.vx;
          dot.vy = -dot.vy;
        } else if (dot.x < 0 || dot.x > canvas.width) {
          dot.vx = -dot.vx;
          // dot.vy = dot.vy;
        }
        dot.x += dot.vx;
        dot.y += dot.vy;
      }
    }

    function connectDots () {
      for (var i = 0; i < dots.nb; i++) {
        for (var j = 0; j < dots.nb; j++) {
          var i_dot = dots.array[i];
          var j_dot = dots.array[j];

          if (
            i_dot.x - j_dot.x < dots.distance &&
            i_dot.y - j_dot.y < dots.distance &&
            i_dot.x - j_dot.x > -dots.distance &&
            i_dot.y - j_dot.y > -dots.distance
          ) {
            if (
              i_dot.x - mousePosition.x < dots.d_radius &&
              i_dot.y - mousePosition.y < dots.d_radius &&
              i_dot.x - mousePosition.x > -dots.d_radius &&
              i_dot.y - mousePosition.y > -dots.d_radius
            ) {
              ctx.beginPath();
              ctx.strokeStyle = averageColorStyles(i_dot, j_dot);
              ctx.moveTo(i_dot.x, i_dot.y);
              ctx.lineTo(j_dot.x, j_dot.y);
              ctx.stroke();
              ctx.closePath();
            }
          }
        }
      }
    }

    function drawDots () {
      for (var i = 0; i < dots.nb; i++) {
        var dot = dots.array[i];
        dot.draw();
      }
    }

    function animateDots () {
      ctx.clearRect(0, 0, canvas.width, canvas.height);
      moveDots();
      connectDots();
      drawDots();

      requestAnimationFrame(animateDots);
    }
    canvas.onmousemove = function (e) {
      mousePosition.x = e.pageX;
      mousePosition.y = e.pageY;
    };
    canvas.onmouseleave = function () {
      mousePosition.x = canvas.width / 3;
      mousePosition.y = canvas.height / 3;
    };

    createDots();
    requestAnimationFrame(animateDots);
  }
};
// Object.assign(obj1,obj2)
// {...obj1,...obj2}
// wx.getAccountInfoSync().miniProgram.appId； //获取本小程序的appid
// flexble.js +pxtorem
// rgba();
// opacity();
</script>

<style></style>
